As an electrostatic capacitive element, that is, a capacitive element included in an LSI (Large Scale Integrated circuit), a so-called MIM (Metal Insulator Metal) capacitor in which a capacitive film is disposed between a lower electrode and an upper electrode formed on a semiconductor substrate is known.
A capacitive value of a MIM capacitor can be set more accurately than other types of capacitive elements such as a MIS (Metal-Insulator-Silicon) capacitor, and the area of a semiconductor device can be reduced by forming a MIM capacitor on a wiring in a layer higher than a semiconductor element. For this reason, MIM capacitors are widely used in various types of semiconductor devices provided with CMOS (Complementary Metal Oxide Semiconductor), BiCMOS (Bipolar Complementary Metal Oxide Semiconductor), and bipolar transistors.
In a MIM capacitor, when the applied voltage becomes equal to or higher than a given voltage, a leakage current rapidly increases. This voltage is referred to as a withstand voltage. In addition, a voltage value at which a leakage current rapidly increases is referred to as a withstand voltage value. A withstand voltage value sometimes varies depending on the quality of a capacitive film, for example, a defect or the like in the capacitive film, and sometimes varies depending on the surface roughness of the lower electrode.
For example, Japanese Patent Application Laid-Open Publication No. 2012-49364 (Patent Document 1) describes a semiconductor device in which the lower electrode of a MIM capacitor is formed by sequentially stacking a first barrier layer, a first aluminum layer, and a second barrier layer from below and the surface roughness of the first aluminum layer is less than a predetermined value. Patent Document 1 describes that, when the planarity of the surface of the first aluminum layer is improved, variations in the withstand voltage of the MIM capacitor is suppressed.
Also, Japanese Patent Application Laid-Open Publication No. 2004-214514 (Patent Document 2) describes a MIM capacitor in which a titanium nitride (TiN) film, a titanium (Ti) film, a lower metal film, a dielectric film, and an upper metal film are sequentially formed from below and the surface of the lower metal film is roughened. According to the Patent Document 2, the capacitance of the MIM capacitor is increased by roughening the surface of the lower metal film.
Furthermore, Japanese Patent Application Laid-Open Publication No. 2003-174096 (Patent Document 3) describes a technique in which, after forming a conductive film serving as a lower electrode of a MIM capacitor, heat treatment is performed at a temperature higher than the formation temperature of the conductive film, thereby reorienting the Al crystal grains contained in the conductive film in a manufacturing process of a semiconductor device.